Bug 1525421 - parse out just the try syntax from the commit message r=tomprince
This mirrors what mozilla-taskcluster does in
https://github.com/taskcluster/mozilla-taskcluster/blob/cb3de4c31e418f7dc1d89cffeeb28ad6a9dae610/src/jobs/taskcluster_graph.js#L46-L58
Differential Revision: https://phabricator.services.mozilla.com/D18748